The invention concerns a procedure for drying a hollow body. It applies particularly but not exclusively to drying containers after they are manufactured and before they are filled, or drying container preforms or blanks during the container manufacturing process. It also concerns a device for implementing the procedure.
As used in this invention, drying is understood to mean a procedure that causes the disappearance of traces of or a small volume of liquid remaining inside or on the walls of a hollow body. Drying is therefore an operation that can follow the draining or emptying of a hollow body after it is cleaned by rinsing or sterilization, requiring the hollow body first to be filled; it can also include the removal of residues or traces of a sterilization agent or any other processing agent that had previously been placed on the inner or outer walls of the hollow body.
Some very special applications of the invention are:
Drying containers that have undergone one of the above-mentioned treatments after they are manufactured and before they are filled, for example cleaning, rinsing, sterilization between the end of the manufacturing line and the beginning of the fill line, or cleaning, rinsing or sterilization after a first usage to prepare for a subsequent use;
Drying plastic (PET, PEN, etc.) container preforms immediately prior to placing them in a sterile machine for manufacturing containers;
Drying tubes or various conduits.
Of course, the examples given above are not restrictive, but are given solely to provide a general idea of the possible field of application of the invention.
The drying procedures and the respective devices known until now are not suitable in this respect because they can not ensure a distribution of the drying agent over the entire inner surface, also called inner wall, of the hollow body, even though it is essentially this surface that should be dried; moreover, the known devices are not xe2x80x9cuniversalxe2x80x9d in this respect, because they do not make it possible to process hollow bodies having different shapes, or they are not suitable for processing any type of material.
One known solution for drying hollow bodies consists of heating said bodies in order to evaporate the liquid remaining therein.
This solution is not suitable for drying containers made of heat-sensitive material, such as containers or the preforms thereof made of polymer plastic (PET, PEN, etc.) because the temperature required to bring about the evaporation could cause deterioration (deformation, change of the physical/chemical properties) of the containers.
Moreover, it is not suitable for high-speed processing.
Another solution consists of injecting hot air into the hollow body.
This solution does not allow proper drying to be achieved at a high rate of speed, nor is it suitable for some hollow body shapes.
In fact, proper, quick drying can not be achieved because the injection of hot air causes compression nodes and anti-nodes to appear in the hollow body, resulting in turbulent phenomena that resist a proper sweep and therefore proper drying of the inside of the hollow body. As a result, the flow of hot air must be applied for a long period of time so that all of the surfaces to be dried are swept. This solution is therefore difficult to apply to some types of heat-sensitive materials because some areas are exposed for a significant amount of time to the flow of hot air, which could cause their deterioration.
This solution is not suitable for drying hollow bodies having special shapes, such as bottles and vials.
The hot air flow is injected through the hollow body""s opening (the neck) which is small in diameter compared to the other parts of the hollow body. The aforementioned phenomena (compression nodes and anti-nodes) are amplified and it is very difficult to dry the inside of the shoulder of these hollow bodies, i.e., the part that bells out between the neck and the body.
The purpose of the invention, therefore, is a procedure and a device with neither of the above-mentioned disadvantages, that is, they make it possible to: dry the entire surface; use the method without significant modification of the device in the event the hollow body to be dried is changed; apply it to any type of hollow body (bottles, pots, vials, bowls, tubes, etc.); apply it to any type of material.
According to the invention, a procedure for drying hollow bodies, particularly containers or preforms of containers, is characterized by the fact that it consists of causing a gaseous entrainment current that carries a drying agent to all of the surfaces in order to distribute it over all of said surfaces.
Thus by entrainment, that is, by guiding the agent over the surfaces, a proper distribution is obtained, unlike the devices that spray or inject the agent inside. A simple entrainment of the agent after it is inserted makes the process usable with any type of material. As will be explained below, the process can be implemented with a relatively simple device usable for any type of hollow body, regardless of their shape or dimensions, and without the need to modify it significantly when the shape and/or dimensions of the body are changed.
Another advantage is that the entrainment of the agent by a gaseous entrainment current allows the drying to be done regardless of the arrangement of the hollow body, that is, regardless of the position of the opening (up, down or otherwise).
According to another characteristic, the insertion of the agent is brought about outside the hollow body, near its opening, and the entrainment current is produced by causing a suction of the agent by using a suction means acting opposite the opening in the hollow body.